Question

A wave of frequency 100Hz travels along a string towards its fixed end. When this wave travels back, after reflection, a node is formed at a distance of 10cm from the fixed end. The speed of the wave (incident and reflected) is?

(a) 20m/s

(b) 40m/s

(c) 5m/s

(d) 10m/s

This question was posed to me by my college professor while I was bunking the class.

My doubt is from Sounds and Waves topic in chapter Waves of Engineering Physics I

Answer 1

Correct option is (a) 20m/s

The explanation: Since a node is formed at the fixed end, so

ʎ/2=10cm or ʎ=20cm

γ=100Hz

v=ʎγ=100×0.20=20m/s.